Ford, who was first lady from 1974 to 1977, shared her struggles with breast cancer and addiction and co-founded the treatment center that bears her name.
Sandler, senior scholar at the Women's Research and Education Institute in Washington, filed the first charges of sex discrimination against 250 educational institutions in 1970. She was instrumental in the passage of the 1972 Title IX law requiring gender equity in every educational program that receives federal funding.
Krone, in 2000, was the first woman to be inducted into the National Museum of Racing and Hall of Fame. In 1993, she became the first woman to win a Triple Crown race when she rode Colonial Affair in the Belmont Stakes. She was also the first woman to win a Breeders' Cup race at the 2003 Juvenile Fillies.
The Hall of Fame says Pelosi, Sandler, Gaskin, Krone and Millett attended. Acceptors attended for the four deceased women including for Ford, who died in 2011.
The inductees join the ranks of suffragist Elizabeth Cady Stanton, tennis pro Billie Jean King, astronaut Sally Ride and actress Lucille Ball. A new class is selected every other year based on the inductees' lasting contributions to society. In all, 247 women have been inducted so far.